1. Field of the Invention
The present invention relates to a needle for a tufting machine.
2. Description of Related Art
A plurality of needles are provided across the width of the tufting machine. Each needle is threaded with an individual yarn when it is spaced from the backing cloth. In operation the point of the needle first penetrates the backing cloth and continuing movement of the needle pulls the yarn through the backing cloth. On the underside of the backing cloth, the yarn is picked up by a hook or looper which holds the loop of yarn while the needle is retracted back through the backing cloth.
The tufting needle was originally developed from a sewing machine needle. In all solid, non-hollow tufting needles, a yarn protection groove is provided running along the shank of the needle to protect the yarn during the needle penetration into the backing material. A hook lead-in chamfer is generally provided to facilitate the pick up of the yarn by the hook from the needle.
According to the present invention there is provided a solid, non-hollow tufting machine needle with a hook lead-in chamfer and without a yarn protection groove.
The inventor has found that, contrary to conventional wisdom, the yarn protection groove is not necessary in a tufting needle and eliminating it can even provide certain advantages.
With a yarn protection groove, the yarn crosses the wall of the yarn protection groove in an angular direction at the point of needle penetration into the backing cloth. Thus results in yarn being trapped between the needle wall and the backing cloth, and also rolls or twists the yarn during the stroke of the needle. This interruption of the yarn flow often creates unevenness on the carpet surface, especially of loop pile fabrics.
Once the yarn has passed through the backing cloth, the yarn protection groove is unnecessary as there is no yarn restriction and adequate clearance.
Thus, in effect, it has been found that the yarn protection groove provides little or no benefit.
By eliminating the yarn protection groove, the needle is stronger and considerably less expensive to manufacture as it does not need to have a complex structure with varying sections of thickness. The manufacturing process can be simplified as multiple die pressing operations and can be reduced or even eliminated.
The invention also opens up the possibility of producing needles from a flat plate, suitable for moulding in a needle module, or a round bar with a machined or a flat pressed working area for single needles which are inserted into round holes drilled in a needle bar.
Also, due to the simplicity of the design, the needles can be produced using conventional machine tools, including wire erosion (EDM) instead of the special purpose machines necessary with the conventional design. The needle can also be moulded in tungsten, powder steel metallurgy and tough nylons.
The additional strength gained by eliminating the groove has resulted in smaller section needles. This, amongst other things, reduces the size of the needle penetration hole in the backing cloth which has significant advantages in tuft retention and backing cloth strength. This is particularly important when tufting into non-woven backing cloths, especially in the automotive industry where backing cloth strength is vital during the moulding operation of carpets.
As the yarn protection groove has been eliminated, the lead-in chamfer can be made wider and more gradual, as compared to a conventional needle thereby improving the hook or looper pick-up.
In order to compensate for the elimination of the yarn protection groove, a chamfer may be provided on the yarn inlet sides of the needle, although this is not believed to be necessary. Alternatively, with a flat plate configuration, the needle can be angled such that the plane of the flat plate is angled with respect to the direction in which, in use, the backing passes through the tufting machine.
In order to smooth the passage of the yarn through the eye, chamfers are preferably provided on the inlet and outlet to the eye.
The invention also extends to a needle module having a plurality of needles according to the invention.
The present invention also extends to a tufting machine having a plurality of needles arranged across the machine, each being arranged to be threaded with an individual yarn when the needle is spaced from a backing material which, in use, is fed through the machine in a direction transverse to the direction in which the needles are arranged, wherein each needle is arranged to penetrate the backing material thereby pulling its yarn through the backing material, and a respective hook or looper is arranged to pick up the loop of yarn from each needle and to hold the loop as the needle is retracted; wherein each needle is a solid, non-hollow needle without a yarn protection groove.